Means for automatically adjusting brake shoes



mi, m36. j wA PAGE www MEANS FOR AUTOMATICALLY ADJUSTING BRAKE sHoEs Filed May 15, 1955 FIG j.

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William Page, liarlilland, liia.

dpplication liiiay l5, i935, Seriali lilo. 21h52@ lil iDlaims.

My invention is particularly applicable to eirpansible brakes for automobile wheels; wherein a pair of oppositely counterpart pivoted shoes, having arcuate outer surfaces provided with linings of friction fabric and supported by astationary spider frame, are thrust apart and against the interior of a cylindrical brake drum. ange on a wheel when it is desired to stop the rotation of the latr.

My invention may be employed with advantage in what is known a's a hydraulic brake system; wherein the brakes are applied by liquid or other iiuid pressure.

The principal purpose and effect of the invention is to automatically adjustably limit the motion of the shoes away from the surface of said braise drum flange when they are released from the pressure which thrusts them into such engagement; so that the minimum amount of clearance between the brake linings and said drum to permit such disengagement when the linings are new is substantially maintained as the linings are worn and in compensation for such wear, until further wear would expose the metal surface of the shoes for contact with the braking surface of the drum. Means may also be provided which, when the latter condition is attained, stop the further automatic adjustment of the shoes and thus prevent scoring of the drum surface there-v with.

My invention includes the various novel features of construction and arrangement hereinafter more definitely specified.

lin said drawing, iig. I is an outside elevation of the spider frame which is fixed to the automobile chassis.

lillg. lili is a vertical sectional view through the fluid cylinder by which pressure is applied to eX- pand the brake shoes to braking position, which cylinder is fixed on the spider frame.

liiig. lll is an elevation of the ratchet bar carried by the left hand shoe in Fig. li and the stationary ratchet plate with which it cooperates,

which is fixed on the stationary spider frame.

llig. lli' is an elevation of a modified` form of ratchet bar provided with said stop means.

liiiig. V is a perspective view of the ratchet plate iii shown in Fig. lili.

lin said figures, the substantially circular spider frame i is conveniently formed ofpressed sheet metal having holes l for bolts by which it may be secured in rigid relation with the chassis of an automobile in .concentric relation with the airis of the wheel, having the brake drum flange t.

frame supports oppositely counterpart brake (ill. lith-79.5)

shoes il which are pivotally supported on the bolts t which are normally stationary in said frame i but may be removed. Said shoes are conveniently formed of pressed sheet metal angle plates having outer flanges i which are arcuate 5 and provided upon their outer surfaces with linings of friction fabric l, conveniently connected therewith by rivets il and adapted to frictionally engage the inner surface of said brake .v flange i which is carried byl the vehicle wheel which is to be stopped."

Said shoes il are connected by the spring i which continually tends to press the free ends thereof toward each other and away from. braking engagement with said brake drinn ange i, The free ends iii of said shoes il are fitted through respective cups i i of soft rubber into engagement with the metal pistons il having cup leathers iii and ntted to reciprocate in the cylinder it which is nxed on the spider frame. Said rubber cups merely serve to exclude dirt from access to said cylinder. Said pistons are normally thrust apart by the spring it interposed between them merely above contemplated includes a reservoir for duid under pressure, in communication with such a cylinder at each wheel to be brahed and a cylinder in the fluid pressure line provided with a 35 plunger which may be operated by a foot or hand lever to augment the pressure in the system so as to apply the brakes. However, any suitable means may be employed for thrusting the bralre shoes il apart, by huid pressure or otherwise, as m the essential part of my invention is the means for automatically adjusting said shoes to com pensate'for wear upon said linings li.

f provide each of said shoes with a pivot stud it rigidly fined therein and extending through a slot ii in a ratchet bar it local to that shoe and having a series of ratchet teeth Each bar is prevented from falling out of engagement with its stub by the head of the latter. Said bars if are respectively associated with ratchet plates iii, 5U each having flanges at right angles, one of which is rigidly connected with said spider frame i and the other, ill', disposed in a vertical plane at right angles to the plane of the local ratchet bar, and having a vertical slot it' receiving and with- M in which said ratchet bar may move vertically and longitudinally; said slot having .at the lower end thereof a single tooth for selective engagement with said ratchet bar teeth Each of said ratchet bars Q2 is normally held down with one of its teeth 23 engaged with its ratchet plate by means of respective springs 2l; each spring hav ing its opposite ends respectively connected with its ratchet bar and said spider frame. The et" fect of said springs il to move the respective ratchet bars downwardly into engagement with the respective teeth each time said bars are moved upwardly in their respective slots 2li' to engage the successive teeth of the hars with the respective single teeth Q5 of the ratchet plates lill, automatically by the ope'ation of the brake mechanism.

The arrangement above described is such that with the shoes il in the retracted position shown.

in li, to which they are stressed by said spring said studs 2li are presented at the inner ends of said slots 2i so that the application oi` pressure to thrust the free ends i of said shoes d apart presses the friction linings l of said shoes outwardly into braking engagement with said wheel flange 3, without disturbing the position in which each or said ratchet bars is initially set; the clearance between said brake shoe linings 'i' and said drum when the braking pressure is released being about twelve-thousandths of an inch, which would be practically invisible in the drawing which is made to a scalewi nine-sixteenths of the full size. Therefore, the clearance space is ei;- aggerated in said drawing.

However, when the linings l are made thinner by wear upon the brake drum iiange 3, outward thrusting movement upon said shoes d causes the studs 2@ to engage the outer ends of the slots 2i in the respective ratchet bars and shift the latter outwardly to engage the next tooth 223 on said bars with the respective ratchet plates fill so that the minimum amount of clearance between the bralre shoe linings and said drum to permit disengagement when the linings are new is substantially maintained as the linings are worn and in compensation `for such wear.

To prevent scoring or the braking surface of the wheel iange 3 by the metal or the brake shoes d when the linings 'i' are entirely worn off; find it convenient to provide ratchet bars such as indicated at t2 in Fig. lV, each having a stop projection liti adapted to encounter the inner surface of the local ratchet plate 24 to stop the outward movement of the brake shoes just short of scraping contact oi the metal thereof with said braking flange However, i do not desire to limit myself to the precise details of construction and arrangement herein set forth, as it is obvious that various modications may be made therein without departing from the essential features of my invention, as delned in the appended claims.

I claim:

1. In automatically adjustable brake mechanism for a vehicle, the combination with a circular brake ange oi a wheel to be braked; oi a spider frame fixed on said vehicle in coaxial relation with said wheel brake flange; a ratchet plate fixed on said frame, and having a xed ratchet, whereby the latter is moved in said plate asador@ to cause its teeth to successively engage said plate tooth; a braise shoe pivoted at one end on said frame, having an arcuate ange for cooperation with said wheel, and having a stud near its other end extending through the slot in said ratchet bar tor limiting the movement of said shoe toward and away from said wheel ange; spring means continually stressing said shoe away from said wheel flange; and means for moving said shoe toward said iiange for braking operation; whereby said ratchet bar is normally held stationary on said spider frame, but is auton matically adjustable toward said wheel angeby said shoe stud when said stud encounters the outer end oi` the slot in said bar before reaching braking relation with. said flange.

2. Mechanism as in claim l, wherein a lining or Yfriction fabric is interposed between said wheel flange and said shoe, and said bar has a stop member i'or engaging said plate and preventing the movement oi said shoe into scraping relation with said flange when said fabric is worn.

3. lin an automatically operative brake mechanism, a brake shoe adjusting device, including a ratchet plate having flanges at right angles; one flange for supporting said plate in. hired position, the other flange having a slot therethrough with. a single ratchet tooth at one edge of said slot; a loose ratchet bar having, near one end, a slot for engaging a projection from a brahe shoe to limit the movement of the latter by the length oi said slot; the other end oi said bar being iitted through said plate slot, and having a series of ratchet teeth along one edge for selective engage-- ment with said plate tooth; and spring means continually stressing said bar ratchet into enm gagement with said plate tooth.

d. A device as in claim 3, wherein the ratchet bar has a stop member for engaging said plate and preventing such adjustment or said would permit the shoe to scrape and score the braking surface.

5. A device as in claim 3, wherein the plate and bar are formed of stampings of primarily :dat sheet metal, and the spring means is iormed oi' wire.

6. A device as in claim 3, wherein the plate and bar are formed of sheet metal stampings, and the spring means is formed of wire md pivotally connected at one end to said bar and at the other end to the plate support.

7. in a brake mechanism ior vehicles, the com bination with a brake shoe and a support which is stationary on the vehicle; oi. a brake shoe adjusting device including ahratchet plate carried by said support and having a vertically disposed slot presenting a single tooth at the lower end thereof, and a flat ratchet bar having one end pivotally connected to said brake shoe and extending through said slot, the lower side of said bar having a series of ratchet teeth for selective engagement with the tooth of said plate, and said bar being vertically movable in said slot about lts pivotal support.

8. In a brake mechanism for vehicles, the com bination with a brake shoe and a support which is stationary on the vehicle; of a brake shoe adjusting device including a pair of members, one connected to said support and the other connected to said brake shoe, one of said members comprising a ratchet bar pivoted at one end to swing in a vertical plane and having a series of ratchet teeth along the under side thereof, and the other of said members comprising a plate disposed in a Vertical plane at right angles to fio Mmmm

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